Android Open Source - tapdefence Utils

From Project

Back to project page tapdefence.

License

The source code is released under:

MIT License

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Java Source Code

package com.kulinich.tapdefence.engine;
//from  ww  w. j a v a2  s .com
public class Utils {
  public static int randsgn() {
    int r = (int) Math.round(Math.random());
    if (r == 0) {
      return -1;
    } else {
      return 1;
    }
  }

  public static float transition(float ratio, float a, float b) {
    return a + (b - a) * (1 - ratio);
  }

  public static float metrics(Point a, Point b) {
    float xs = b.x - a.x;
    float ys = b.y - a.y;
    return (float) (Math.sqrt(xs * xs + ys * ys));
  }

  // (c) Alexander Hristov
  // http://www.ahristov.com/tutorial/geometry-games/intersection-segments.html
  public static Point intersect(Line a, Line b) {
    float x1 = a.a.x;
    float x2 = a.b.x;
    float x3 = b.a.x;
    float x4 = b.b.x;
    float y1 = a.a.y;
    float y2 = a.b.y;
    float y3 = b.a.y;
    float y4 = b.b.y;
    float d = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);
    if (d == 0) {
      return null;
    }
    float xi = ((x3 - x4) * (x1 * y2 - y1 * x2) - (x1 - x2)
        * (x3 * y4 - y3 * x4))
        / d;
    float yi = ((y3 - y4) * (x1 * y2 - y1 * x2) - (y1 - y2)
        * (x3 * y4 - y3 * x4))
        / d;

    Point p = new Point(xi, yi);
    if (xi < Math.min(x1, x2) || xi > Math.max(x1, x2)) {
      return null;
    }
    if (xi < Math.min(x3, x4) || xi > Math.max(x3, x4)) {
      return null;
    }
    return p;
  }
}

Java Source Code List